In pursuit of counteracting today's environmental problems, corporate management will have to implement organizational changes factoring in sustainability, which is why it is important to understand exactly what leads managers to initiate these changes. It has been established that managers' personal values are critical for their behavior and that threats to these values can mobilize managers to change their actions. However, when confronted with environment-related threats, managers may face value conflicts and various tensions between their aim to implement sustainable changes and their desire to fulfill business requirements of their job positions. Only recently have researchers begun to investigate the underlying beliefs that may lead managers to initiate organizational change toward sustainability. Borrowing theoretical assumptions from the domain of health psychology (from the well-established health belief model), the present conceptual article develops an environmental belief model that specifies when exactly threats lead managers to initiate organizational change. The environmental belief model proposes that environment-related threats trigger change (i) when managers believe that their firms are susceptible to these threats, (ii) the threats are considered as serious for the company, (iii) the perceived benefits of the change outperform (iv) the perceived barriers, and when there is (v) an external cue (e.g., an information campaign). All these propositions are supported with empirical findings from business contexts. Besides theoretical advancement on the role of environmental threats as precipitators of organizational change, the model provides guidance on how to frame environment-related threats that will mobilize managers for organizational change toward sustainability.